Turkish riot police. Witnesses report there were no Kurdish protesters on the sidestreet where Mazlum Akay, 11, was heading. Photograph: Bulent Kilic/AFP/Getty Images

On a recent summer evening 11-year-old Mazlum Akay left his home in Yüregir, a predominantly Kurdish neighbourhood in the southern Turkish city of Adana, to buy sweets at the local corner shop.

Nearby, clashes had broken out between riot police and local youths demonstrating against the solitary confinement of Kurdish militant leader Abdullah Öcalan, who was convicted for treason in 1999.

Witnesses say that there were no protesers on the sidestreet where Mazlum was heading to the shop, but the schoolboy was struck on the head by a police teargas cartridge. Eight days later, on 5 August, Mazlum died from his wounds and became the 501st child killed by Turkish security forces since 1988, according to Turkish human rights organisations.

Osman Kara, an activist of the Human Rights Association in Adana told the Guardian: "The disproportionate force that the government uses against civilians is to blame for this high number. There simply is no reason whatsoever for an 11-year-old child to die in the street like this." And he added: "Up until today, no serious investigation has been made regarding the deaths of children in this conflict. This is another reason that [the police and the armed forces] do not flinch to use force against them."

Around 1,500 people attended Mazlum's funeral this week, and his family say they plan to sue the police over his death. Neither the governor's office nor the police authority in Adana have made any public statements on the case. The family said that the doctors were optimistic when Mazlum first arrived at the hospital. "But he started to vomit, and vomited blood all night", his mother, 46-year-old Ayse Akay explained. "In the morning, they performed another scan and discovered bleeding in the brain. Shortly after that, Mazlum fell into a coma." She has three other sons and four daughters. "Why did they hurt my little boy? He has done nothing wrong!"

The family also says that the police came to their house and intimidated them. "They told us 'not to blow this out of proportion', Mustafa Akay said. "They also claimed that the injury was caused by a stone." However, eyewitnesses had found the empty cartridge and the hospital confirmed that Mazlum had indeed been hit by the projectile.

"The police confiscated the original of the doctor's report", said 62-year-old Akay. "But I had made a photocopy beforehand, because we know that the police routinely take doctors' reports away."

Unrest in Kurdish neighbourhoods is rarely reported by the Turkish media, but Durmaz Özmen, the Yüregir county commissioner of the main pro-Kurdish party BDP underlined that the death of 11-year-old Mazlum Akar would ignite further anger: "Frustration levels are high, and even if the case of Mazlum Akay will not be reported in the mainstream Turkish media, people here will remember it for a long time." And he continued: "The Turkish government has turned its back on the Kurds and the Kurdish issue: "They say they want freedom in Syria. But how can you try and clean up the neighbourhood if you don't sweep in front of your own door first?"